High-K gate dielectric and metal gate conductor stack for planar field effect transistors formed on type III-V semiconductor material and silicon germanium semiconductor material

ABSTRACT

An electrical device that includes a substrate including a first region of a type III-V semiconductor material and a second region of a type IV germanium containing semiconductor material. An n-type planar FET is present in the first region of the substrate. A p-type planar FET is present in a second region of the substrate. A gate structure for each of the n-type planar FET and the p-type planar FET includes a metal containing layer including at least one of titanium and aluminum atop a high-k gate dielectric. An effective work function of the gate structure for both the n-type and p-type planar FETs is a less than a mid gap of silicon.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to Ser. No. 14/828,202, entitled “HIGH-KGATE DIELECTRIC AND METAL GATE CONDUCTOR STACK FOR FIN-TYPE FIELD EFFECTTRANSISTORS FORMED ON TYPE III-V SEMICONDUCTOR MATERIAL AND SILICONGERMANIUM SEMICONDUCTOR MATERIAL” which is incorporated herein in itsentirety by reference.

FIELD OF THE INVENTION

The present disclosure relates generally to semiconductor devices, andmore particularly to work function modifications in semiconductordevices.

BACKGROUND

Field effect transistors (FETs) are widely used in the electronicsindustry for switching, amplification, filtering and other tasks relatedto both analog and digital electrical signals. Most common among theseare metal oxide semiconductor field effect transistors (MOSFET or MOS),in which a gate structure is energized to create an electric field in anunderlying channel region of a semiconductor body, by which electronsare allowed to travel through the channel between a source region and adrain region of the semiconductor body. Complementary MOS (CMOS) deviceshave become widely used in the semiconductor industry, wherein bothn-type and p-type (NMOS and PMOS) transistors are used to fabricatelogic and circuitry.

Continuing trends in semiconductor device manufacturing include areduction in electrical device feature size (scaling), as well asimprovements in device performance in terms of device switching speedand power consumption. Some examples of methods to improve deviceswitching include adjusting the work function of the materials in thegate structure.

SUMMARY

In one aspect of the present disclosure, an electrical device isprovided that includes a planar FET semiconductor devices formed on typeIV semiconductor surfaces including germanium (Ge) and type III-Vsemiconductor surfaces, in which the planar FETs are formed using gatefirst processing or gate last processing and use the substantially thesame gate structures for n-type and p-type devices. In one embodimentthat uses gate last processing, the electrical device includes asubstrate including a first region of a type III-V semiconductormaterial and a second region of a type IV germanium containingsemiconductor material. An n-type planar FET is present in the firstregion of the substrate, and a p-type planar FET is present in a secondregion of the substrate. A gate structure for each of the n-type planarFET and the p-type planar FET includes a metal containing layerincluding at least one of titanium and aluminum atop a high-k gatedielectric, wherein a work function of the gate structure for both then-type and p-type planar FETs is a less than mid gap of silicon. In oneembodiment, the mid gap of silicon is 4.65 eV.

A composition for the gate structure to the n-type planar FET may besubstantially the same as a composition of the gate structure to thep-type planar FET, and in some embodiments, an effective work functionfor each of the n-type planar FET and the p-type planar FET ranges from4.4 eV to 4.6 eV.

In some embodiments, the metal containing layer comprises titaniumnitride. In other embodiments, the metal containing layer comprises astack of a first titanium nitride on the high-k gate dielectric, atitanium aluminum carbide layer on the first titanium nitride layer, anda second titanium nitride layer on the titanium aluminum carbide layer,or the metal containing layer comprises a stack of a first titaniumnitride on the high-k gate dielectric, a titanium aluminide layer on thefirst titanium nitride layer, and a second titanium nitride layer on thetitanium aluminide layer.

In one example, the first and second gate structure further comprises aninterface layer doped with group IIA or IIIB dopants between the high-kgate dielectric and the substrate.

In another aspect of the present disclosure, a method of forming anelectrical device is provided that includes planar FETs that are formedusing a gate first process. In one embodiment, the method may includeproviding a substrate including a first region of a type III-Vsemiconductor material and a second region of a type IV germaniumcontaining semiconductor material. At least one gate stack is formedover the first and second region of the substrate, in which the gatestack includes an interface layer, a high-k gate dielectric layer, ametal nitride layer and a conductive electrode layer. The gate stack maybe patterned to provide a first gate structure in the first region and asecond gate structure in the second region of the substrate. N-typesource and drain regions may be formed on opposing sides of the firstgate structure for a planar n-type FET in the first region of thesubstrate; and p-type source and drain regions may be formed on opposingsides of the second gate structure for a planar p-type FET. An effectivework function of the gate structure for both the n-type and p-typeplanar FETs is a less than mid gap of silicon.

In some examples, the metal nitride layer comprises titanium nitridedeposited using atomic layer deposition (ALD) or Physical VaporDeposition (PVD). The titanium nitride of the first gate structure andthe second gate structure may be stoichiometrically tuned, by changingthe Ti to N ratio during the PVD sputtering process, for appropriatework function shifts that result in an effective work function in therange of 4.4 eV to 4.6 eV. In some other embodiments, a composition ofthe gate structure to the n-type planar FET is substantially the same asa composition of the gate structure to the p-type planar FET. In someembodiments, the gate first processing may be conducted at temperaturesless than 600° C.

In another aspect of the present disclosure, a method of forming anelectrical device including planar FETs is provided that uses a gatelast process sequence. The method may include providing a substrateincluding a first region of a type III-V semiconductor material and asecond region of a type IV germanium containing semiconductor material.Replacement gate structures may be formed in the first and secondregions of the substrate. N-type source and drain regions may be formedin the first region of the substrate and p-type source and drain regionsmay be formed in the second region of the substrate. The replacementgate structures may be substituted with functional gate structures. Thefunctional gate structures may include a high-k gate dielectric and gateconductor including at least one aluminum containing layer in each ofthe first and second region of the substrate, wherein the work functionfor the gate structure for an n-type planar FET in the first region ofthe substrate and p-type planar FET is the second region of thesubstrate is less than a mid gap value of silicon.

In some examples, the gate conductor including the at least one aluminumcontaining layer includes a stack of a first titanium nitride on thehigh-k gate dielectric, a titanium aluminum carbide layer on the firsttitanium nitride layer, and a second titanium nitride layer on thetitanium aluminum carbide layer, or the at least one aluminum containinglayer includes a stack of a first titanium nitride on the high-k gatedielectric, a titanium aluminide layer on the first titanium nitridelayer, and a second titanium nitride layer on the titanium aluminidelayer.

DESCRIPTION OF THE DRAWINGS

The following detailed description, given by way of example and notintended to limit the invention solely thereto, will best be appreciatedin conjunction with the accompanying drawings, wherein like referencenumerals denote like elements and parts, in which:

FIG. 1 is a side cross-sectional view depicting a planar n-type fieldeffect transistor (FET) on a first portion of a substrate composed of atype III-V semiconductor material, and a planar p-type field effecttransistor (FET) on a second portion of the substrate composed of agermanium containing material, in which the n-type and p-type fieldeffect transistors include work function adjustments and are formedusing gate first methods, in accordance with one embodiment of thepresent disclosure.

FIG. 2 is a side cross-sectional view depicting forming the materiallayers for a first gate structure and a second gate structure to asubstrate having a first portion composed of type III-V semiconductormaterial and a second portion composed of a germanium containingsemiconductor material, in accordance with one embodiment.

FIG. 3 is a side cross-sectional view depicting patterning the materiallayers to provide a first gate structure in the first portion of thesubstrate, and a second gate structure in the second portion of thesubstrate.

FIG. 4 is a side cross-sectional view depicting forming a block maskover the first portion of the substrate, and forming p-type source anddrain regions in the second portion of the substrate, in accordance withone embodiment of the present disclosure.

FIG. 5 is a side cross-sectional view depicting a planar n-type fieldeffect transistor (FET) on a first portion of a substrate composed of atype III-V semiconductor material, and a planar p-type field effecttransistor (FET) on a second portion of the substrate composed of agermanium containing material, in which the n-type and p-type fieldeffect transistors include work function adjustments and are formedusing gate last methods, in accordance with one embodiment of thepresent disclosure.

FIG. 6 is a side cross-sectional view depicting forming replacement gatestructures on a first portion of a substrate that is comprised of a typeIII-V semiconductor material and second portion of the substrate that iscomprised of a germanium containing semiconductor material, inaccordance with one embodiment of the present disclosure.

FIG. 7 is a side cross-sectional view depicting forming n-type sourceand drain regions in a first portion of the substrate, and formingp-type source and drain regions in a second portion of the substrate, inaccordance with one embodiment of the present disclosure.

FIG. 8 is a side cross-sectional view depicting forming an interleveldielectric layer over the structure depicted in FIG. 7, and removing thefirst and second replacement gate structures, in accordance with oneembodiment of the present disclosure.

DETAILED DESCRIPTION

Detailed embodiments of the methods and structures of the presentdisclosure are described herein; however, it is to be understood thatthe disclosed embodiments are merely illustrative of the disclosedmethods and structures that may be embodied in various forms. Inaddition, each of the examples given in connection with the variousembodiments of the disclosure are intended to be illustrative, and notrestrictive. Further, the figures are not necessarily to scale, somefeatures may be exaggerated to show details of particular components.Therefore, specific structural and functional details disclosed hereinare not to be interpreted as limiting, but merely as a representativebasis for teaching one skilled in the art to variously employ themethods and structures of the present disclosure.

References in the specification to “one embodiment”, “an embodiment”,“an example embodiment”, etc., indicate that the embodiment describedmay include a particular feature, structure, or characteristic, butevery embodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed. For purposes of the description hereinafter, the terms“upper”, “lower”, “right”, “left”, “vertical”, “horizontal”, “top”,“bottom”, and derivatives thereof shall relate to the invention, as itis oriented in the drawing figures. The terms “overlying”, “atop”,“positioned on” or “positioned atop” means that a first element, such asa first structure, is present on a second element, such as a secondstructure, wherein intervening elements, such as an interface structure,e.g. interface layer, may be present between the first element and thesecond element. The term “direct contact” means that a first element,such as a first structure, and a second element, such as a secondstructure, are connected without any intermediary conducting, insulatingor semiconductor layers at the interface of the two elements.

The present disclosure is related to forming complementary metal oxidesemiconductor (CMOS) devices, in which the p-type conductivitysemiconductor devices, e.g., planar field effect transistors (FETs), areformed on a silicon and germanium containing semiconductor surface, suchas silicon germanium (SiGe), and the n-type conductivity semiconductordevices, e.g., planar field effect transistors (FETs), are formed on atype III-V semiconductor surface, e.g., indium gallium arsenide(InGaAs), in which the gate structures of the n-type and p-typesemiconductor devices have had work function adjustments. As usedherein, “semiconductor device” refers to an intrinsic semiconductormaterial that has been doped, that is, into which a doping agent hasbeen introduced, giving it different electrical properties than theintrinsic semiconductor. Doping involves adding dopant atoms to anintrinsic semiconductor, which changes the electron and hole carrierconcentrations of the intrinsic semiconductor at thermal equilibrium.Dominant carrier concentration in an extrinsic semiconductor determinesthe conductivity type of the semiconductor. In the followingdescription, the semiconductor device is a field effect transistor.Complementary metal oxide semiconductor (CMOS) is a type ofsemiconductor that use both N-type (negative polarity) and P-type(positive polarity) semiconductor circuits. Typically, since only one ofthe circuit types is on at any given time, CMOS chips require less powerthan chips using just one type of transistor. A “field effecttransistor” is a transistor in which output current, i.e., source-draincurrent, is controlled by the voltage applied to a gate structure. Afield effect transistor typically has three terminals, i.e., a gatestructure, source region and drain region. As used herein, the term“source” is a doped region in the semiconductor device, in whichmajority carriers are flowing into the channel. As used herein, the term“channel” is the region underlying the gate structure and between thesource and drain of a semiconductor device that becomes conductive whenthe semiconductor device is turned on. As used herein, the term “drain”means a doped region in semiconductor device located at the end of thechannel, in which carriers are flowing out of the transistor through thedrain. A “gate structure” means a structure used to control outputcurrent (i.e., flow of carriers in the channel) of a semiconductingdevice through electrical or magnetic fields.

The term “planar” as used to describe a semiconductor deviceorientation, e.g., planar FET, denotes that the direction of chargecarriers from the source region to the drain region of the semiconductordevice is along a plane that is parallel to the upper surface of thesubstrate, wherein a gate structure is present on the upper surface ofthe substrate. In a planar semiconductor device, the gate structure doesnot wrap around the sidewalls of the channel region as in a finstructure.

The term “work function” is used to describe a gate electrode materialthat determines the threshold voltage of a semiconductor device. Forexample, a work function adjustment effectuates a threshold voltageshift either towards the valence band or conduction band. As usedherein, “threshold voltage” is the lowest attainable gate voltage thatwill turn on a semiconductor device, e.g., transistor, by making thechannel of the device conductive. A “valence band” is the highest rangeof electron energies where electrons are normally present at absolutezero.

The “conduction band” is the lowest lying electron energy band of thedoped material that is not completely filled with electrons.

It has been determined that III-V nFET/SiGe pFET CMOS devices canrequire specific work function engineering, i.e., work functionadjustments, to enable the appropriate functioning planar FET devicesdue to the different affinities of type III-V semiconductors, such asindium gallium arsenide (InGaAs) and germanium containingsemiconductors, such as silicon germanium (SiGe), in comparison toconventional silicon (Si) substrates, e.g., single crystalline-Si(c-Si).

In some embodiments, the methods and structures disclosed herein providea single metal high-k metal gate stack to enable planar dual channelCMOS devices using III-V nFETs and SiGe pFETs (planar nFET and planarpFET). In some examples of CMOS arrangements including planar FETs, boththe nFET and pFET gate stacks, require effective work functions (EWF)ranging from 4.4 to 4.6 eV for planar dual channel CMOS. The effectivework function is defined relative to the vacuum level and extractedusing measured C-V curves on silicon (Si), i.e., EWF of the gate stackis extracted from a CV curve of the gate stack deposited on silicon, andincludes the work function of the electrode along with fixed charges anddipoles within the dielectric.

FIG. 1 depicts a planar n-type field effect transistor (FET) 100 a on afirst portion 15 of a substrate 10 that is composed of a type III-Vsemiconductor material, and a planar p-type field effect transistor(FET) 100 b on a second portion 20 of the substrate 10 that is composedof a germanium containing material. The n-type and p-type field effecttransistors 100 a, 100 b each include work function adjustments and areformed using a gate first method. The first portion 15 of the substrate10 may be separated from the second portion 20 of the substrate 10 by anisolation region 9, such as a shallow trench isolation (STI) regions,which in one example can be composed of silicon oxide (SiO₂).

The term “III-V semiconductor material” denotes a semiconductor materialthat includes at least one element from Group IIIB of the Periodic Tableof Elements under the Old International Union of Pure and AppliedChemistry (IUPAC) classification system, or Group 13 of the NewInternational Union of Pure and Applied Chemistry classification system;and at least one element from Group VB of the Periodic Table ofElements, or Group 15 of the New International Union of Pure and AppliedChemistry classification system. In some embodiments, the III-Vsemiconductor material that is present in the first portion 15 of thesubstrate may be selected from the group of (AlSb), aluminum arsenide(AlAs), aluminum nitride (AlN), aluminum phosphide (AlP), galliumarsenide (GaAs), gallium phosphide (GaP), indium antimonide (InSb),indium arsenic (InAs), indium nitride (InN), indium phosphide (InP),aluminum gallium arsenide (AlGaAs), indium gallium phosphide (InGaP),aluminum indium arsenic (AlinAs), aluminum indium antimonide (AlInSb),gallium arsenide nitride (GaAsN), gallium arsenide antimonide (GaAsSb),aluminum gallium nitride (AlGaN), aluminum gallium phosphide (AlGaP),indium gallium nitride (InGaN), indium arsenide antimonide (InAsSb),indium gallium antimonide (InGaSb), aluminum gallium indium phosphide(AlGaInP), aluminum gallium arsenide phosphide (AlGaAsP), indium galliumarsenide phosphide (InGaAsP), indium arsenide antimonide phosphide(InArSbP), aluminum indium arsenide phosphide (AlInAsP), aluminumgallium arsenide nitride (AlGaAsN), indium gallium arsenide nitride(InGaAsN), indium aluminum arsenide nitride (InAlAsN), gallium arsenideantimonide nitride (GaAsSbN), gallium indium nitride arsenide aluminumantimonide (GaInNAsSb), gallium indium arsenide antimonide phosphide(GaInAsSbP), and combinations thereof. The germanium containing materialthat provides the second portion 20 of the substrate 10 may besubstantially 100 at. % germanium (Ge), e.g., greater than 95 at %germanium (Ge), such as 99 at. % germanium (Ge), silicon germanium(SiGe), silicon germanium doped with carbon (SiGe:C) or combinationsthereof. It is noted that in one example, the III-V semiconductormaterial that provides the first portion 15 of the substrate 10 isIn_(0.53)Ga_(0.47)As, and the germanium containing material thatprovides the second portion 20 of the substrate 10 is silicon germanium(SiGe) having greater than 50 at. % germanium. It is noted that theabove atomic percent that are provide to describe the material of thefirst and second portions 15, 20 of the substrate describe a basematerial, i.e., intrinsic semiconductor, which does not include ameasurement of the dopants that provided the conductivity type of thedevice, e.g., whether the FET is a p-type or n-type FET.

Each of the n-type and p-type field effect transistors 100 a, 100 binclude a gate structure having work function adjustments, which in someembodiments provides an effective work function ranging from 4.3 to 4.7eV for each of the n-type and p-type field effect transistors 100 a, 100b. The n-type field effect transistor 100 a may include a first gatestructure 30 a that includes a first interface dielectric layer 31 aformed on the channel region of the first portion 15 of the substrate10; a first high-k gate dielectric layer 32 a that is present on thefirst interface dielectric layer 31 a; a first metal work functionadjusting layer 33 a that is present on the first high-k gate dielectriclayer 32 a; and a first conductive electrode 34 a. The p-type fieldeffect transistor 100 b may include a second gate structure 30 b thatincludes a second interface dielectric layer 31 b formed on the channelregion of the second portion 20 of the substrate 10; a second high-kgate dielectric layer 32 b that is present on the second interfacedielectric layer 31 b; a second metal work function adjusting layer 33 bthat is present on the second high-k gate dielectric layer 32 b; and asecond conductive electrode 34 b.

The first and second interface dielectric layer 31 a, 31 b may be anoxide, such as silicon oxide (SiO₂). In some embodiments, the first andsecond interface dielectric layers 31 a, 31 b may also be provided by adoped dielectric material. For example, the first and second interfacedielectric layers 31 a, 31 b may be comprised of a silicon containinglayer and a layer containing a dopant selected from Group IIA or GroupIIIB of the periodic table of elements under the Old International Unionof Pure and Applied Chemistry (IUPAC) classification system. Examples ofdielectric dopants may be selected from the group consisting ofberyllium (Be), magnesium (Mg), barium (Ba), lanthanum (La), yttrium (Y)and combinations thereof. For example, at least one of the first andsecond interface dielectric layer 31 a, 31 b may be composed oflanthanum oxide (La₂O₃). The thickness for each of the first and secondinterface dielectric layer 31 a, 31 b may range from 1 Å to 10 Å. Insome examples, the thickness for each of the first and second interfacedielectric layers 31 a, 31 b may be on the order of 2 Å to 6 Å.

The term “high-k” as used to describe the first and second high-k gatedielectric layers 32 a, 32 b denotes a dielectric material having adielectric constant greater than silicon oxide (SiO₂) at roomtemperature (20° C. to 25° C.) and atmospheric pressure (1 atm). Forexample, a high-k dielectric material may have a dielectric constantgreater than 4.0. In another example, the high-k gate dielectricmaterial has a dielectric constant greater than 7.0. In someembodiments, the first and second high-k gate dielectric layers 32 a, 32b are composed of a hafnium-based dielectric. The term ‘Hf-baseddielectric’ is intended herein to include any high k dielectriccontaining hafnium (Hf). Examples of such Hf-based dielectrics comprisehafnium oxide (HfO₂), hafnium silicate (HfSiO_(X)), Hf siliconoxynitride (HfSiON) or multilayers thereof. In some embodiments, theHf-based dielectric comprises a mixture of HfO₂ and ZrO₂ or rare earthoxide such as La₂O₃. MgO or MgNO can also be used. Typically, theHf-based dielectric is hafnium oxide or hafnium silicate. Hf-baseddielectrics typically have a dielectric constant that is greater thanabout 10.0. In one embodiment, the thickness for each of the first andsecond high-k gate dielectric layers 32 a, 32 b is greater than 0.8 nm.More typically, the at least one first gate dielectric layer 13 has athickness ranging from about 1.0 nm to about 6.0 nm.

The first and second gate structures 30 a, 30 b may be formed using asingle metal electrode, i.e., first and second metal work functionadjusting layer 33 a, 33 b and first and second conductive electrode 34a, 34 b, for both of the first and second gate structures 30 a, 30 b. Bysingle metal electrode it is meant that the composition for both thefirst and metal work function adjusting layers 33 a, 33 b, as well asthe composition for both of the first and second gate electrode 34 a, 34b, is the same. For example, the first and second metal work functionadjusting layers 33 a, 33 b may each be composed of metal nitride, suchas titanium nitride (TiN). In some examples, stoichiometry tuning oftitanium nitride (TiN) may be used to for fine tuning the work functionadjustments provided by the first and second metal work functionadjusting layers 33 a, 33 b. Stoichiometric tuning can be accomplishedby adjusting the titanium (Ti) to nitrogen (N) ratio during the physicalvapor deposition (PVD) sputtering program for forming the materiallayer. Although titanium nitride (TiN) is described above as anembodiment of a material suitable for the first and second metal workfunction adjusting layers, other metal nitrides may be suitable for usewith the present disclosure. For example, the metal layers may furthercomprise aluminum. In other examples, the first and second metal workfunction adjusting layers may include other metals from Groups IVB toVIB in the Periodic Table, including, e.g., tantalum nitride (TaN),niobium nitride (NbN), vanadium nitride (VN), tungsten nitride (WN), andthe like with a thickness of about 20 Angstroms to about 30 Angstroms.

The conductive electrodes 34 a, 34 b may be composed of any metalcontaining material. For example, the conductive electrodes 34 a, 34 bmay be composed of tungsten (W) or a tungsten including alloy. In otherexamples, the conductive electrodes 34 a, 34 b are composed of aluminum(Al), copper (Cu), platinum (Pt), silver (Ag) or an alloy thereofincluding allows with tungsten (W).

The first and second gate structures 30 a, 30 b is suitable foractivation anneals for the source and drain regions of the n-type planarFET 100 a and the p-type planar FET 100 b at temperatures of greaterthan 500° C. and less than 600° C. for gate first processing.

Still referring to FIG. 1, a gate sidewall spacer 35 is present on eachof the gate structures 30 a, 30 b. The gate sidewall spacer 35 may becomposed of any dielectric material, such as silicon oxide or siliconnitride.

The n-type planar FET 100 a includes n-type dopants in the first portion15 of the substrate 10 for the source region 40 a and drain region 45 athat are positioned on opposing sides of the first gate structure 30 a.In some embodiments, a n-type dopant in a type III-V semiconductormaterial, such as InGaAs, can be element from Group IIA or VIA of thePeriodic Table of Elements). As used herein, “n-type” refers to theaddition of impurities that contributes free electrons to an intrinsicsemiconductor. In some embodiments, the dopant for providing an n-typedevice in a type III-V semiconductor material may be from Group IV ofthe periodic table of elements, such as silicon. Dopant atoms from groupIV, such a silicon (Si), have the property that they can act asacceptors or donor depending on whether they occupy the site of groupIII or group V atoms respectively.

The p-type planar FET 100 b includes p-type dopants in the secondportion 20 of the substrate 10 for the source region 40 b and drainregion 45 b that are positioned on opposing sides of the second gatestructure 30 b. As used herein, “p-type” refers to the addition ofimpurities to an intrinsic semiconductor that creates deficiencies ofvalence electrons. In a type IV semiconductor surface, such as thegermanium containing second portion 20, e.g., silicon germanium (SiGe)second portion 20, of the substrate, examples of p-type dopants, i.e.,impurities, include but are not limited to boron, aluminum, gallium andindium. The p-type dopant within the source and drain regions 40 b, 45 bis typically present in a concentration ranging from about 10¹¹ to about10¹⁵ atoms/cm², with a concentration of dopant within the doped regionfrom about 10¹¹ to about 10¹³ atoms/cm² being more typical.

Although not depicted in the supplied figures the source and drainregions 40 a, 40 b, 45 a, 45 b for the p-type planar FET 100 b and then-type planar FET 100 a may further include raised source and drainregions. Raised source and drain regions may include in-situ dopedepitaxially formed semiconductor material that is formed on the uppersurface of the substrate 10 in which the source and drain regions 40 a,40 b, 45 a, 45 b are present.

Referring to FIG. 1, in some embodiments, the first gate structure 30 ato the n-type planar semiconductor device 100 a is composed of a firstconductive electrode 34 a of tungsten (W), a first metal work functionlayer 33 a of titanium nitride (TiN), a first high-k gate dielectriclayer 32 a of hafnium oxide (HfO₂), and an interface oxide of siliconoxide (SiO₂), in which the first gate structure 30 a is present on afirst portion 15 of the substrate 10 that is composed ofIn_(0.53)Ga_(0.47)As, and the effective work function for the first gatestructure 30 a to the n-type planar semiconductor device 100 a rangesfrom 4.4 eV to 4.6 eV. The p-type planar semiconductor device 100 b ispresent on the same substrate 10 as the n-type planar semiconductordevice 100 a. The p-type planar semiconductor device 100 b may have thesame gate structure as the first gate structure 30 a for the n-typeplanar semiconductor device 100 a. In one example, the second gatestructure 30 b to the p-type planar semiconductor device 100 b iscomposed of a second conductive electrode 34 b of tungsten (W), a secondmetal work function layer 33 b of titanium nitride (TiN), a secondhigh-k gate dielectric layer 32 b of hafnium oxide (HfO₂), and aninterface layer 31 b of silicon oxide (SiO₂), in which the first gatestructure 30 b is present on a second portion 20 of the substrate 10that is composed of silicon germanium (SiGe) having a germanium (Ge)concentration that is greater than 50 at. %, and the effective workfunction for the first gate structure 30 a to the p-type planarsemiconductor device 100 b ranges from 4.4 eV to 4.6 eV.

In another embodiment, the aforementioned effective work functions (EWF)can be provided for each of the p-type planar semiconductor device andthe n-type planar semiconductor device using a titanium nitride (TiN)atomic layer deposition (ALD) formed material layer for the first andsecond metal work function adjusting layers 33 a, 33 b in combinationwith a first and second interface layer 31 a, 31 b comprising dopingwith Group IIA and/or Group IIIB dielectric doping.

Although the semiconductor devices described herein are field effecttransistors (FETs), the present disclosure is equally applicable to anysemiconductor device that exhibits a change in conductivity in responseto the application of a threshold voltage.

The CMOS device depicted in FIG. 1 may be formed using a gate firstprocess that is described with reference to FIGS. 2-5.

FIG. 2 depicts one embodiment of forming the material layers for a firstgate structure 30 a and a second gate structure 30 b on a substrate 10having a first portion 15 composed of type III-V semiconductor materialand a second portion 20 composed of a germanium containing semiconductormaterial. The different compositions of the first and second portions15, 20 of the substrate 10 can be formed using epitaxial growth, layertransfer, bonding, and deposition processes to position the differentcomposition materials on a base substrate 8, such as a bulk siliconwafer. The isolation regions 9 separating the first portion 15 of thesubstrate 10 from the second portion 20 of the substrate 10 can beformed by etching a trench utilizing a dry etching process, such asreactive-ion etching (RIE) or plasma etching. A deposition process isused to fill the trench with oxide grown from tetraethylorthosilicate(TEOS) precursors, high-density oxide or another like trench dielectricmaterial. After trench dielectric fill, the structure may be subjectedto a planarization process.

The interface layer 31 may be formed using a thermal oxidation method.For example, when the interface layer 31 is composed of silicon oxide itcan be formed using thermal oxidation. In the embodiments, in which theinterface layer 31 is formed with a group IIA or group IIIB dielectricdoping layer, the interface layer 31 may be formed using a depositionmethod, such as chemical vapor deposition (CVD) or atomic layerdeposition (ALD). Variations of CVD processes suitable for forming theinterface layer 31 include, but not limited to, Atmospheric Pressure CVD(APCVD), Low Pressure CVD (LPCVD) and Plasma Enhanced CVD (PECVD),Metal-Organic CVD (MOCVD) and combinations thereof may also be employed.

In the embodiment depicted in FIG. 2, the interface layer 31 is a singlelayer having the same composition for both of the first and secondportions 15, 20 of the substrate 10. Embodiments have been contemplated,in which the composition of the interface layer 31 that is present onthe first portion 15 of the substrate 10 is different than thecomposition of the interface layer 31 that is present on the secondportion 20 of the substrate 10. The different portions, i.e., first andsecond portion 15, 20, of the substrate 10 may be independentlyprocessed by forming a first block mask over one portion of thesubstrate and processing the exposed portion, followed by removing thefirst block mask, forming a second block mask over the previouslyprocessed portion and processing the newly exposed portion.

The high-k gate dielectric layer 32 can be formed by a thermal growthprocess such as, for example, oxidation, nitridation or oxynitridation.The high-k gate dielectric layer 32 can also be formed by a depositionprocess such as, for example, chemical vapor deposition (CVD),plasma-assisted CVD, metal-organic chemical vapor deposition (MOCVD),atomic layer deposition (ALD), evaporation, reactive sputtering,chemical solution deposition and other like deposition processes. Thehigh-k gate dielectric layer 32 may also be formed utilizing anycombination of the above processes. The high-k gate dielectric layer 32typically has a thickness ranging from 1 nm to 10 nm. In one example,the high-k gate dielectric layer 32 has a thickness ranging from 2 nm to5 nm. The high-k gate dielectric layer 32 may be composed of a singlecomposition high-k dielectric layer that provides the same compositionfor the first and second high-k gate dielectric layers 32 a, 32 bfollowing gate patterning.

Referring to FIG. 2, following formation of the high-k gate dielectriclayer 32, the first and second metal work function adjusting layers 33a, 33 b may be formed. In one embodiment, a work function metal layercomprising titanium nitride (TiN) may be deposited by a physical vapordeposition (PVD) method, such as sputtering. Examples of sputteringapparatus that may be suitable for depositing the work function metallayer include DC diode type systems, radio frequency (RF) sputtering,magnetron sputtering, and ionized metal plasma (IMP) sputtering. Inaddition to physical vapor deposition (PVD) techniques, the p-type workfunction metal layer may also be formed using chemical vapor deposition(CVD) and atomic layer deposition (ALD).

In some embodiments, the first and second metal work function adjustinglayers 33 a, 33 b can be formed with the deposition of a single layer ofwork function adjusting material. In this example, the composition ofthe first metal work function layer 33 a is the same as the compositionof the second metal work function layer 33 b. In the example that isdepicted in FIG. 2, the composition of the first metal work functionlayer 33 a can be different than the composition of the second metalwork function layer 33 b. The different portions, i.e., first and secondportion 15, 20, of the substrate 10 may be independently processed toprovide a first metal work function layer 33 a having a different thanthe composition of the second metal work function layer 33 b by forminga first block mask over one portion of the first and second portions 15,20 of the substrate 10 and processing the exposed portion. Once one ofthe first and second metal work function layer 33 a, 33 b is formed onthe substrate, the first block mask is removed. A second block mask maybe formed over the portion of the substrate in which the work functionmetal layer was previously formed leaving another portion of thesubstrate exposed. A second work function metal layer may then be formedon the exposed portion of the substrate. The second block mask may thenbe removed. The block masks may be soft masks, e.g., photoresist masks,or the block masks may be hard masks, e.g., a mask composed of a nitrideor oxide material.

In one embodiment, each of the first and second metal work functionadjusting layers 33 a, 33 b may be formed of titanium nitride withstoichiometric tuning to provide the appropriate work functionadjustments for the n-type field effect transistor 100 a and the p-typefield effect transistor 100 b. Stoichiometric tuning can be accomplishedby adjusting the titanium (Ti) to nitrogen (N) ratio during the physicalvapor deposition (PVD) sputtering program for forming the materiallayer. In some embodiments, the titanium nitride layers may be formedusing atomic layer deposition (ALD).

Still referring to FIG. 2, a conductive electrode layer 34 may be formedon the first and second metal work function layers 33 a, 33 b. Theconductive electrode layer 34 may be blanket deposited overlying boththe first and second metal work function layers 33 a, 33 b. Theconductive electrode layer 34 may be deposited using a physical vapordeposition method. For example, the conductive electrode layer 34 may bedeposited using plating, electroplating, electroless plating, sputteringand combinations thereof. Examples of sputtering apparatus that may besuitable for depositing the work function metal layer include DC diodetype systems, radio frequency (RF) sputtering, magnetron sputtering, andionized metal plasma (IMP) sputtering. In addition to physical vapordeposition (PVD) techniques, the conductive electrode layer 34 may alsobe formed using chemical vapor deposition (CVD).

FIG. 3 is depicts patterning the material layers depicted in FIG. 2 toprovide a first gate structure 30 a in the first portion 15 of thesubstrate 10, and a second gate structure 30 b in the second portion 20of the substrate 10. The patterned gate structures 30 a, 30 b are formedutilizing photolithography and etch process steps. Specifically, apattern is produced by applying a photoresist to the surface to beetched; exposing the photoresist to a pattern of radiation; and thendeveloping the pattern into the photoresist utilizing conventionalresist developer. Once the patterning of the photoresist is completed,the sections covered by the photoresist are protected while the exposedregions are removed using a selective etching process that removes theunprotected regions. As used herein, the term “selective” in referenceto a material removal process denotes that the rate of material removalfor a first material is greater than the rate of removal for at leastanother material of the structure to which the material removal processis being applied. The etch process for etching the exposed portions ofthe interface layer 31, the high-k gate dielectric layer 32, the firstand second metal work function layers 33 a, 33 b, and the conductiveelectrode layer 34 may include an anisotropic etch, such as reactive ionetching (RIE). Following the etch process, the remaining portions of theinterface layer provide the first and second interface layer 31 a, 31 b,the remaining portions of the high-k dielectric layer provide the firstand second high-k dielectric layer 32 a, 32 b, and the remainingportions of the conductive electrode layer 34 provide the first andsecond conductive electrodes 34 a, 34 b.

Referring to FIG. 4, a gate sidewall spacer 35 may then be formed oneach of the first and second gate structures 30 a, 30 b. The gatesidewall spacer 35 may be composed of oxide, i.e., SiO₂, but may alsocomprise nitride or oxynitride materials. Each gate sidewall spacer 35may have a width ranging from 50.0 nm to 100.0 nm. The gate sidewallspacer 35 can be formed by deposition and etch processes.

FIG. 4 further depicts implanting dopants into the second portion 20 ofthe substrate 10 to provide a p-type source region 40 b and a p-typedrain region 45 b. The source regions 40 a, 40 b and drain regions 45 a,45 b for the planar semiconductor devices are formed ion implantation.In the embodiment that is depicted in FIG. 4, a block mask 50 is formedover the first portion 15 of the substrate 10 in which the n-type sourceregion 40 a, and p-type drain region 45 a is formed. After the p-typesource region 40 b and p-type drain region 45 b is formed in the secondregion 20 of the substrate 10, the n-type source region 40 a and n-typedrain region 45 a can then be formed in the first portion 15 of thesubstrate 10. This can begin with removing the block mask 50, andforming another block mask (not shown) over the second portion 20 of thesubstrate 10, in which the p-type source region 40 a and the p-typedrain region 45 b have been formed. The block mask that is formed overthe second portion 20 of the substrate 10 leaves the first portion 15 ofthe substrate 10 exposed. The n-type source region 40 a and n-type drainregion 40 b may then be formed in the first portion 15 of the substrate10.

Although FIG. 4 only depicts forming source and drain regions within thesurface of the first and second portions 15, 20 of the substrate 10. Thepresent disclosure is not limited to only this example. For example,raised source and drain regions may be present on the upper surfaces ofthe first and second portions 15, 20 on opposing sides of the gatestructures 30 a, 30 b. The raised source and drain regions may be formedof epitaxially deposited semiconductor material and may have the samedopant conductivity as the source and drain region 40 a, 40 b, 45 a, 45b that the epitaxial material is formed on.

Following formation of the source and drain regions 40 a, 40 b, 45 a, 45b they may be activated using an activation anneal. For example, theanneal process may include a temperature greater than 500° C.

The above process sequence can provide the CMOS device depicted in FIG.1, including a first gate structure 30 a to the n-type planarsemiconductor device 100 a that is composed of a first conductiveelectrode 34 a of tungsten (W), a first metal work function layer 33 aof titanium nitride (TiN), a first high-k gate dielectric layer 32 a ofhafnium oxide (HfO₂), and an interface oxide of silicon oxide (SiO₂), inwhich the first gate structure 30 a is present on a first portion 15 ofthe substrate 10 that is composed of In_(0.53)Ga_(0.47)As, and theeffective work function for the first gate structure 30 a to the n-typeplanar semiconductor device 100 a ranges from 4.4 eV to 4.6 eV. Thep-type planar semiconductor device 100 b is present on the samesubstrate 10 as the n-type planar semiconductor device 100 a. The p-typeplanar semiconductor device 100 b may have the same gate structure asthe first gate structure 30 a for the n-type planar semiconductor device100 a. In one example, the second gate structure 30 b to the p-typeplanar semiconductor device 100 b is composed of a second conductiveelectrode 34 b of tungsten (W), a second metal work function layer 33 bof titanium nitride (TiN), a second high-k gate dielectric layer 32 a ofhafnium oxide (HfO₂), and an interface oxide of silicon oxide (SiO₂), inwhich the first gate structure 30 b is present on a second portion 20 ofthe substrate 10 that is composed of silicon germanium (SiGe) having agermanium (Ge) concentration that is greater than 50 at. %, and theeffective work function for the first gate structure 30 a to the n-typeplanar semiconductor device 100 a ranges from 4.4 eV to 4.6 eV.

The present disclosure also provide methods and structures for providingwork function adjustments for CMOS devices having planar n-type FETsformed on III-V semiconductor materials, and planar p-type FETs formedon germanium containing semiconductor materials using gate lastprocessing, which may also be referred to as replacement gate processingor replacement metal gate (RMG) processing. FIG. 5 depicts oneembodiment of a planar n-type field effect transistor (FET) 100 c on afirst portion 15 of a substrate 10 composed of a type III-Vsemiconductor material, and a planar p-type field effect transistor(FET) 110 d on a second portion 20 of the substrate 10 composed of agermanium containing material, in which the n-type and p-type fieldeffect transistors include work function adjustments and are formedusing gate last methods.

The substrate 10 that is depicted in FIG. 5 has been described abovewith reference to FIG. 1. Therefore, the description of the substrate 10including the description of the first portion 15 and the second portion20, as well as the base substrate 8 and the isolation region 9, that hasbeen provided above with reference to FIG. 1 is suitable for thedescription of these similarly labeled elements in FIG. 5. For example,in one embodiment, the first portion 15 of the substrate 10 depicted inFIG. 5 is composed of a type III-V semiconductor material, such asIn_(0.53)Ga_(0.47)As, and the second portion 20 of the substrate 10 iscomposed of a germanium (Ge) containing material, such as silicongermanium (SiGe) with greater than 50 at % Germanium (Ge). The workfunction adjustments made using the first and second gate structures 30a, 30 b depicted in FIG. 5 that are provided in the present disclosurecan produce an effective work function (EWF) for each of the n-type andp-type planar FETs 100 c, 100 d that ranges from 4.3 eV to 4.7 eV.

Similar to the n-type field effect transistor 100 a that is depicted inFIG. 1., the n-type field effect transistor 100 c depicted in FIG. 5 mayinclude a first gate structure 30 a that includes a first interfacedielectric layer 31 c formed on the channel region of the first portion15 of the substrate 10; a first high-k gate dielectric layer 32 c thatis present on the first interface dielectric layer 31 a; a first metalwork function adjusting layer 33 c that is present on the first high-kgate dielectric layer 32 c; and a first conductive electrode 34 c.

The description of the first interface dielectric layer 31 a, and thefirst conductive electrode 34 a, of the n-type field effect transistor100 a that is depicted in FIG. 1 is suitable for the description of thefirst interface dielectric layer 31 c, and the first conductiveelectrode 34 c that is depicted in FIG. 5. The first high-k dielectriclayer 32 c that is depicted in FIG. 5 includes a horizontal base portionand two vertical sidewall portions, which result from the gate lastprocess for forming the gate structures. With the exception of theU-shaped geometry of the first high-k gate dielectric layer 32 c that isdepicted in FIG. 5, the description of the first high-k gate dielectriclayer 32 a that is depicted in FIG. 1 is suitable for the description ofthe first high-k gate dielectric layer 32 c that is depicted in FIG. 5.For example, the first high-k gate dielectric layer 32 c may be composedof hafnium oxide (HfO₂).

The first metal work function adjusting layer 33 c that is present inthe first gate structure 30 a to the n-type planar FET 100 c formedusing gate last processing may be a composite layer, i.e., amulti-layered structure, including at least one aluminum (Al) containinglayer. For example, the first metal work function adjusting layer 33 cmay be composed of a first layer of titanium nitride (TiN) that ispresent on the first high-k dielectric layer 32 c, a second layer oftitanium aluminum carbide (TiAlC) that is present on the first layer oftitanium nitride (TiN), and a third layer of titanium nitride (TiN) thatis present on the second layer of titanium aluminum carbide (TiAlC). Inanother example, the first metal work function adjusting layer 33 c maybe composed of a first layer of titanium nitride (TiN) that is presenton the first high-k dielectric layer 32 c, a second layer of titaniumaluminide (TiAl) that is present on the first layer of titanium nitride(TiN), and a third layer of titanium nitride (TiN) that is present onthe second layer of titanium aluminide (TiAl). The thickness of eachlayer in the composite layer that provides the first metal work functionadjusting layer may range from about 10 Angstroms to about 60 Angstroms.

Similar to the p-type field effect transistor 100 b that is depicted inFIG. 1., the p-type field effect transistor 100 d depicted in FIG. 5 mayinclude a second gate structure 30 b that includes a second interfacedielectric layer 31 d formed on the channel region of the second portion20 of the substrate 10; a second high-k gate dielectric layer 32 d thatis present on the second interface dielectric layer 31 d; a second metalwork function adjusting layer 33 d that is present on the second high-kgate dielectric layer 32 d; and a second conductive electrode 34 d.

The description of the second interface dielectric layer 31 b, and thesecond conductive electrode 34 b, of the p-type field effect transistor100 b that is depicted in FIG. 1 is suitable for the description of thesecond interface dielectric layer 31 d, and the second conductiveelectrode 34 d that is depicted in FIG. 5. The second high-k dielectriclayer 32 d that is depicted in FIG. 5 includes a horizontal base portionand two vertical sidewall portions, which result from the gate lastprocess. With the exception of the U-shaped geometry of the secondhigh-k gate dielectric layer 32 d that is depicted in FIG. 5, thedescription of the second high-k gate dielectric layer 32 b that isdepicted in FIG. 1 is suitable for the description of the second high-kgate dielectric layer 32 d that is depicted in FIG. 5. For example, thesecond high-k gate dielectric layer 32 d may be composed of hafniumoxide (HfO₂).

The second metal work function adjusting layer 33 d that is present inthe second gate structure 30 b to the p-type planar FET 100 d formedusing gate last processing may be a composite layer, i.e., amulti-layered structure, including at least one aluminum (Al) containinglayer. For example, the second metal work function adjusting layer 33 dmay be composed of a first layer of titanium nitride (TiN) that ispresent on the second high-k dielectric layer 32 d, a second layer oftitanium aluminum carbide (TiAlC) that is present on the first layer oftitanium nitride (TiN), and a third layer of titanium nitride (TiN) thatis present on the second layer of titanium aluminum carbide (TiAlC). Inanother example, the second metal work function adjusting layer 33 d maybe composed of a first layer of titanium nitride (TiN) that is presenton the second high-k dielectric layer 32 d, a second layer of titaniumaluminide (TiAl) that is present on the first layer of titanium nitride(TiN), and a third layer of titanium nitride (TiN) that is present onthe second layer of titanium aluminide (TiAl). The thickness of eachlayer in the composite layer that provides the second metal workfunction adjusting layer 33 d may range from about 30 Angstroms to about60 Angstroms.

The composition of each material layer in the first gate structure 30 amay be the same as the composition of each material layer in the secondgate structure 30 b. In some embodiments, the composition of at leastone material layer in the first gate structure 30 a may be differentfrom the composition of at least one material layer in the second gatestructure 30 b.

Referring to FIG. 5, a gate sidewall spacer 35 is present on each of thegate structures 30 a, 30 b. The gate sidewall spacer 35 may be composedof any dielectric material, such as silicon oxide or silicon nitride.The p-type planar FET 100 b includes p-type dopants in the secondportion 20 of the substrate 10 for the source region 40 b and drainregion 45 b that are positioned on opposing sides of the second gatestructure 30 b. The n-type planar FET 100 a includes n-type dopants inthe first portion 15 of the substrate 10 for the source region 40 a anddrain region 45 a that are positioned on opposing sides of the firstgate structure 30 a. Further details regarding the dopants used toprovide the source and drain regions 40 a, 40 b, 45 a, 45 b are providedabove in the description of FIG. 1. Although not depicted in FIG. 5, thesource and drain regions 40 a, 40 b, 45 a, 45 b for the p-type planarFET 100 d and the n-type planar FET 100 c may further include raisedsource and drain regions.

Still referring to FIG. 5, an interlevel dielectric layer 55 is presentoverlying the source and drain regions 40 a, 40 b, 45 a, 45 b and has anupper surface that is coplanar with an upper surface of the first andsecond gate structures 30 a, 30 b. As will be described below, theinterlevel dielectric 55 is formed prior to removing a replacement gatestructure, also referred to as sacrificial gate structure. The first andsecond gate structures 30 a, 30 b are formed after the replacement gatestructures are removed, and the u-shaped geometry is indicative of thegate last methodology.

Referring to FIG. 5, in some embodiments, the first gate structure 30 ato the n-type planar semiconductor device 100 c is composed of a firstconductive electrode 34 c of tungsten (W), a first metal work functionlayer 33 c that is a composite of TiN/TiAlC/TiN or a composite ofTiN/TiAl/TiN, a first high-k gate dielectric layer 32 c of hafnium oxide(HfO2), and an interface oxide of silicon oxide (SiO₂), in which thefirst gate structure 30 a is present on a first portion 15 of thesubstrate 10 that is composed of In0.53Ga0.47As, and the effective workfunction for the first gate structure 30 a to the n-type planarsemiconductor device 100 c ranges from 4.4 eV to 4.6 eV. The p-typeplanar semiconductor device 100 d is present on the same substrate 10 asthe n-type planar semiconductor device 100 c, as depicted in FIG. 5. Thep-type planar semiconductor device 100 d may have the same gatestructure as the first gate structure 30 a for the n-type planarsemiconductor device 100 c. In one example, the second gate structure 30b to the p-type planar semiconductor device 100 d is composed of asecond conductive electrode 34 d of tungsten (W), a second metal workfunction layer 33 d that is a composite of TiN/TiAlC/TiN or a compositeof TiN/TiAl/TiN, a second high-k gate dielectric layer 32 d of hafniumoxide (HfO₂), and an interface oxide 31 d of silicon oxide (SiO₂), inwhich the second gate structure 30 b is present on a second portion 20of the substrate 10 that is composed of silicon germanium (SiGe) havinga germanium (Ge) concentration that is greater than 50 at. %, and theeffective work function for the first gate structure 30 a to the n-typeplanar semiconductor device 100 a ranges from 4.4 eV to 4.6 eV.

The CMOS device depicted in FIG. 2 may be formed using a gate lastprocess that is described with reference to FIGS. 6-8.

FIG. 6 depicts forming replacement gate structures 60 on a first portion15 of a substrate 10 that is comprised of a type III-V semiconductormaterial and second portion 20 of the substrate 10 that is comprised ofa germanium containing semiconductor material. In some embodiments, thereplacement gate structures 60 that are depicted in FIG. 6 are formed ofa semiconductor material, such as polysilicon. But, in otherembodiments, the replacement gate structures 60 may be composed of adielectric material. The replacement gate structures 60 may be formedusing deposition, photolithography and etching processes, similar to thefunctional gate structures that are described above with reference toFIG. 2. The replacement gate structures 60 are formed to have a geometrythat matches the geometry of the later formed functional gatestructures.

FIG. 7 depicts forming n-type source and drain regions 40 a, 45 a in thefirst portion 15 of the substrate 10, and forming p-type source anddrain regions 40 b, 45 b in a second portion 20 of the substrate 10. Thesource and drain regions 40 a, 40 b, 45 a, 45 b depicted in FIG. 7 maybe formed using ion implantation while the replacement gate structures60 are present on the substrate 10. The source and drain regions 40 a,40 b, 45 a, 45 b that are depicted in FIG. 7 are similar to the sourceand drain regions 40 a, 40 b, 45 a, 45 b that are depicted in FIGS. 1, 4and 5. Therefore, the above description of the source and drain regions40 a, 40 b, 45 a, 45 b that are depicted in FIGS. 1, 4 and 5 is suitablefor providing further details regarding the source and drain regions 40a, 40 b, 45 a, 45 b that are depicted in FIG. 7.

The method may continue with activating the source and drain regions 40a, 40 b, 45 a, 45 b. Activation of the source and drain regions 40 a, 40b, 45 a, 45 b may be done with the replacement gate structure present onthe substrate 10. This provides that the later formed functional gatestructure is not subjected to the high temperature anneal process.Further details regarding the activation anneal have been describedabove with reference to FIGS. 1-4.

FIG. 8 depicts one embodiment of forming an interlevel dielectric layer55 over the structure depicted in FIG. 7, and removing the first andsecond replacement gate structures 60. The interlevel dielectric layer55 may be deposited on the structure depicted in FIG. 7, using chemicalsolution deposition, spin on deposition, chemical vapor deposition or acombination thereof. The interlevel dielectric layer 55 may be selectedfrom the group consisting of silicon containing materials such as SiO₂,Si₃N₄, SiO_(x)N_(y), SiC, SiCO, SiCOH, and SiCH compounds, theabove-mentioned silicon containing materials with some or all of the Sireplaced by Ge, carbon doped oxides, inorganic oxides, inorganicpolymers, hybrid polymers, organic polymers such as polyamides or SiLK™,other carbon containing materials, organo-inorganic materials such asspin-on glasses and silsesquioxane-based materials, and diamond-likecarbon (DLC), also known as amorphous hydrogenated carbon, α-C:H).Additional choices for the interlevel dielectric layer include any ofthe aforementioned materials in porous form, or in a form that changesduring processing to or from being porous and/or permeable to beingnon-porous and/or non-permeable. Following deposition, the interleveldielectric layer 55 may be planarized to provide an upper surface thatis coplanar with an exposed upper surface of the replacement gatestructures 60. In one example, the planarization process is chemicalmechanical planarization (CMP). Once, the replacement gate structures 60are exposed, they may be removed using a selective etch process.

After the replacement gate structures 60 are removed, gate openings 65are present to the channel regions of the first portion 15 of thesubstrate 10 and the second portion 15 of the substrate 10. The gateopenings 65 may then be filled with the material layers that provide thefunction gate structures for each of the n-type planar FET 100 c and thep-type planar FET 100 d, as depicted in FIG. 5. For example, eachinterface layer 31 c, 31 d may be provided by thermal growth or chemicalvapor deposition. The high-k gate dielectrics 32 c, 32 d may be formedusing chemical vapor deposition (CVD), such as plasma enhanced chemicalvapor deposition (PECVD). Thereafter, the first metal work functionlayer 33 c and the second metal work function metal layer 33 d may beformed using a deposition method, such as atomic layer deposition (ALD)or physical vapor deposition (PVD). Examples of physical vapordeposition (PVD) used to form each of the first and second metal workfunction layer 33 c, 33 d can include sputtering methods or platingmethods. The first and second conductive electrodes 34 c, 34 d may bedeposited using a physical vapor deposition (PVD) method, such asplating, e.g., electroplating. It is noted that in the embodiments, inwhich the composition of the first gate structure 30 a is the same asthe second gate structure 30 b, the materials layers for both gatestructures may be formed simultaneously. In some embodiments, thematerial layers for one of the gate structures 30 a, 30 b may be formedindependently than the material layers in the other gate structures 30a, 30 b. This can be accomplished using block masks, as described in theabove embodiments. By employing block masks, at least one of thematerial layers for the first gate structure 30 a may have a compositionthat is different than the material layers in the second gate structure30 b.

In some embodiments, the gate last process flow that is illustrated withreference to FIGS. 5-8 may employ a tungsten fill for the first andsecond conductive electrodes 34 a, 34 b with a 400° C. process flow. Ina replacement gate process flow, i.e., gate last process flow, theelectrodes are not chemically or thermally stable for temperaturesgreater than 400° C., and can lead to unwanted threshold voltage shifts.

While the present invention has been particularly shown and describedwith respect to preferred embodiments thereof, it will be understood bythose skilled in the art that the foregoing and other changes in formsand details may be made without departing from the spirit and scope ofthe present invention. It is therefore intended that the presentinvention not be limited to the exact forms and details described andillustrated, but fall within the scope of the appended claims.

The invention claimed is:
 1. A method of forming an electrical deviceincluding planar FETs using a gate first process comprising: providing asubstrate including a first region of a type III-V semiconductormaterial and a second region of a type IV germanium containingsemiconductor material; forming at least one gate stack comprising aninterface layer, a high-k gate dielectric layer, a metal nitride layerand a conductive electrode layer over the first and second region of thesubstrate; patterning the gate structure to provide a first gatestructure in the first region and a second gate structure in the secondregion; and forming n-type source and drain regions on opposing sides ofthe first gate structure for a planar n-type FET in the first region ofthe substrate and p-type source and drain regions on opposing sides ofthe second gate structure for a planar p-type FET, wherein a workfunction of the gate structure for both the n-type and p-type planarFETs is a less than mid gap of silicon.
 2. The method of claim 1,wherein the metal nitride layer comprises titanium nitride depositedusing atomic layer deposition (ALD).
 3. The method of claim 1, whereinthe metal nitride layer comprises titanium nitride, and wherein thetitanium nitride of the first and second gate structure isstoichiometrically tuned to achieve an effective work function in arange of 4.4 eV-4.6 eV.
 4. The method of claim 1, wherein a compositionof the first gate structure to the n-type planar FET is substantiallythe same as a composition of the second gate structure to the p-typeplanar FET.
 5. The method of claim 1, wherein an effective work functionfor each of the n-type planar FET and the p-type planar FET ranges from4.4 eV to 4.6 eV.
 6. A method of forming an electrical device includingplanar FETs using a gate last process comprising: providing a substrateincluding a first region of a type III-V semiconductor material and asecond region of a type IV germanium containing semiconductor material;forming replacement gate structures in the first and second regions ofthe substrate; forming n-type source and drain regions in the firstregion of the substrate and p-type source and drain regions in thesecond region of the substrate; and replacing the replacement gatestructures with functional gate structures comprising a high-k gatedielectric and gate conductor including at least one aluminum containinglayer in each of the first and second region of the substrate, whereinan effective work function for the gate structure for an n-type planarFET in the first region of the substrate and p-type planar FET is thesecond region of the substrate is less than a mid gap value of silicon.7. The method of claim 6, wherein the effective work function for eachof the n-type planar FET and the p-type planar FET ranges from 4.4 eV to4.6 eV.
 8. The method of claim 6, wherein the gate conductor includingthe at least one aluminum containing layer comprises a stack of a firsttitanium nitride on the high-k gate dielectric, a titanium aluminumcarbide layer on the first titanium nitride layer, and a second titaniumnitride layer on the titanium aluminum carbide layer, or the at leastone aluminum containing layer comprises a stack of a first titaniumnitride on the high-k gate dielectric, a titanium aluminide layer on thefirst titanium nitride layer, and a second titanium nitride layer on thetitanium aluminide layer.
 9. The method of claim 6 further comprising aconductive electrode atop the gate conductor for the functional gatestructures to the n-type planar FET and the p-type planar FET, wherein acomposition of the conductive electrode to the n-type planar FET issubstantially the same as a composition of the conductive electrode tothe p-type planar FET.
 10. The method of claim 6 further comprising aninterfacial layer between the high-k gate dielectric of each of thefunctional gate structures and the substrate.
 11. The method of claim 6,wherein the type IV germanium containing semiconductor material issilicon germanium (SiGe) or germanium (Ge).